Field of the Invention
The present disclosure relates to a transfer film for attaching protection film to flat panel display and method for manufacturing the flat panel display using the same. Especially, the present disclosure relates to a transfer film having protection films temporarily to prevent an organic light emitting diode display device (OLED) from moisture and a method for manufacturing the OLED using the same.
Discussion of the Related Art
Nowadays, various flat panel display devices are developed for overcoming many drawbacks of the cathode ray tube such as heavy weight and bulk volume. The flat panel display devices include the liquid crystal display device (or LCD), the field emission display (or FED), the plasma display panel (or PDP) and the electroluminescence display device (or ED).
The electroluminescence display device is categorized in the inorganic light emitting diode display device and the organic light emitting diode display device according to the luminescence material. As a self-emitting display device, the electroluminescence display device has the merits those the response speed is very fast, the brightness is very high and the view angle is large. FIG. 1 illustrates the structure of the organic light emitting diode according to the related art. Referring to FIG. 1, the organic light emitting diode comprises the organic light emitting material layer, and the cathode and the anode which are facing each other with the organic light emitting material layer therebetween. The organic light emitting material layer comprises the hole injection layer HIL, the hole transport layer HTL, the emission layer EML, the electron transport layer ETL and the electron injection layer EIL.
The organic light emitting diode radiates the lights due to the energy from the excition formed at the excitation state in which the hole and the electron are recombined at the emission layer EML. The organic light emitting display device represents the video data by controlling the light brightness from the emission layer EML of the organic light emitting diode.
The organic light emitting diode display (or OLED) using the organic light emitting diode can be categorized in the passive matrix type organic light emitting diode display (or PMOLED) and the active matrix type organic light emitting diode display (or AMOLED). Furthermore, according to the direction of the emitted light, it can be categorized in the top emission type and the bottom emission type.
By representing any video/image in the natural color, the organic light emitting diode display is currently coming into the lime light, and widely applied in various field including the portable personal information devices such as cellular phone, smart phone or PDAs. The OLED is the self luminescence display having the high responding speed less than 1 ms and the low power consumption, for representing natural full color images/videos. Furthermore, it has wide view angle covering near 180 degree, and it is best device for display regardless of diagonal size. Its manufacturing method is very simple, based on the low temperature process and the conventional semiconductor processing technologies.
However, the OLED is very weak from oxygen and moisture. In order to ensure the reliability of the OLED property, until now, the glass substrate having a getter is used for encapsulation of the organic light emitting material. As the requirement and needs for the thin and flexible display are increased, the glass substrate may be exchanged by film type encapsulation as the protecting film for the OLED panel.
Hereinafter, referring to FIGS. 2A and 2B, we will explain how to attaching the protection film to the OLED according to the related art. FIGS. 2A and 2B are perspective views illustrating the processes for attaching the protection film to the organic light emitting diode display panel.
As shown in FIG. 2A, in the related art, after placing the protection film FF on the transferring substrate PT at each pattern using a metal jig MM, the protection film FF is transferred to the organic light emitting diode display panel.
In order to maintain the shape, the metal jig MM is made of rigid metal material. The metal jig MM has a plurality of pattern hole HO at which each protection film FF is located. As well known to ordinary skilled person, a plurality of the OLED panels are arrayed in a matrix pattern, on one large mother substrate MG, each protection film FF is attached on each organic light emitting diode display panel, and then a plurality of the unit OLED displays are completed by cutting the mother substrate MG.
The metal jig MM is combined with the transferring substrate PT. Each protection film FF is located at each pattern hole HO formed at the metal jig MM. At this time, the protection film FF is located as the adhesive surface is facing upward. The adhesive may be the thermal hardening epoxy resin.
Referring to FIG. 2B, a mother substrate MG having a plurality of organic light emitting diode display panels OLED is located on the metal jig MM. By aligning each organic light emitting diode display panel OLED with each protection film FF relatively, the mother substrate MG is placed on the metal jig MM. After that, keeping the chamber temperature to 70° C. to melt the adhesive, the protection films FF are attached on the organic light emitting diode display panels OLED. At the same time, keeping the chamber in vacuum condition, the protection films FF and the organic light emitting diode display panels OLED should be firmly closed to each other. After that, increasing the temperature of the chamber up to 100° C. for hardening the adhesive, the protection films FF are permanently attached on the organic light emitting diode display panels OLED.
Like this, as the method for attaching the protection film to the organic light emitting diode display panel OLED according to the related art is conducted under vacuum condition, the vacuum facility is required. Furthermore, for hardening the adhesive, the oven system is also required. Especially, aligning the substrate with the metal jig and conducting processes in oven and vacuum chamber through a manual processes, the method according to the related art is not proper to apply In-line type facility for mass production. That is, the related art cannot ensure enough yields for establishing the mass production system.
In addition, as the protection film is attached to the organic light emitting diode display panel under vacuum condition, when the air is not perfectly out, air bubble may be formed so that the protection film may not be attached correctly. Especially, as the rigid large substrate should be attached to the transferring substrate having rigid structure, it is hard to completely eliminate the air bubble between them so that the final product may have defects on representing images/videos.